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Ransom.Win64.CROSSLOCK.THDAHBC

June 02, 2023
 Analysis by: Jeffrey Francis Bonaobra
 ALIASES:

Ransom:Win32/lockbit!MSR (MICROSOFT), UDS:Trojan.Win32.DelShad.lfy (KASPERSKY)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

2,713,088 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 Apr 2023

Payload:

Disables AV, Terminates processes, Encrypts files, Displays windows

Arrival Details

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Ransomware adds the following processes:

  • %System%\notepad.exe → used to patch ntdll.dll and bypass ETW
  • cmd.exe /c "wevtutil cl application"
  • cmd.exe /c "vssadmin delete shadows /all /quiet"
  • cmd.exe /c "wbadmin DELETE SYSTEMSTATEBACKUP -deleteOldest"
  • cmd.exe /c "wbadmin DELETE SYSTEMSTATEBACKUP"
  • cmd.exe /c "wbadmin delete catalog -quiet"
  • cmd.exe /c "bcdedit /set {default} recoveryenabled No"
  • cmd.exe /c "bcdedit /set {default} bootstatuspolicy ignoreallfailures"
  • cmd.exe /c "wevtutilcl system"
  • cmd.exe /c "wevtutilcl security"
  • If the parameter --uac or -ub is used and the executable is executed without administrative privileges:
    • cmd.exe /c "reg add HKCU\Software\Classes\mscfile\shell\open\command /ve /d \"{Malware File Path}\{Malware File Name}\" /f"
    • cmd.exe /c "C:\windows\system32\eventvwr.exe"
    • cmd.exe /c "reg delete HKCU\Software\Classes\mscfile /f"
  • If the parameter combination --host or -H, --user or -u, and --pwd or -p is used:
    • cmd.exe /c "net use \{Host Name}\IPC$ /u:{Username} {Password}"

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Process Termination

This Ransomware terminates the following services if found on the affected system:

  • SQLSERVERAGENT
  • SQLTELEMETRY
  • MSSQLSERVER
  • WIDWriter
  • SQLWriter
  • vss
  • sql
  • svc$
  • memtas
  • mepocs
  • sophos
  • veeam
  • backup
  • GxVss
  • GxBlr
  • GxFWDG
  • GxCVDG
  • GxCIMgr
  • DefWatch
  • ccEvtMgr
  • ccSetMgr
  • SavRoam
  • RTVscan
  • QBFCService
  • QBIDPService
  • Intuit
  • QuickBooks.
  • FCS
  • QBCFMonitorService
  • YooBackup
  • YooIT
  • zhudongfangyu
  • sophos
  • stc_raw_agent
  • VSNAPVSS
  • VeeamTransportSvc
  • VeeamDeploymentService
  • VeeamNFSSvc
  • veeam
  • PDVFSService
  • BackupExecVSSProvider
  • BackupExecAgentAccelerator
  • BackupExecAgentBrowser
  • BackupExecDiveciMediaService
  • BackupExecJobEngine
  • BackupExecManagementService
  • BackupExecRPCService
  • AcrSch2Svc
  • AcronisAgent
  • CASAD2DWebSvc
  • CAARCUpdateSvc

It terminates the following processes if found running in the affected system's memory:

  • sql
  • oracle
  • ocssd
  • dbsnmp
  • synctime
  • agntsvc
  • isqlplussvc
  • xfssvccon
  • mydesktopservice
  • ocautoupds
  • encsvc
  • firefox
  • tbirdconfig
  • mydesktopqos
  • ocomm
  • dbeng50
  • sqbcoreservice
  • excel
  • infopath
  • msaccess
  • mspub
  • onenote
  • outlook
  • powerpnt
  • steam
  • thebat
  • thunderbird
  • visio
  • winword
  • wordpad
  • notepad
  • sqlwriter
  • sqlservr
  • javaw
  • java
  • bpjava-susvc
  • nbproxy
  • avrd
  • tldd
  • bpdbm
  • vmd
  • bpjobd
  • bprd
  • nbpem
  • nbjm
  • bpcd
  • bpinetd
  • nbemm
  • nbaudit
  • nbars
  • nbvault
  • nbstserv
  • nbsvcmon
  • nbsl
  • nbrb
  • nbrmms
  • vnetd
  • nbim
  • nbevtmgr
  • nbdisco
  • nbatd
  • ltid
  • pbx_exchange
  • dbsrv17
  • bpcompatd
  • secfsd

Other Details

This Ransomware does the following:

  • It checks if the process is executed in a WINE environment.
  • It bypasses Event Tracing for Windows by patching the ntdll.dll module.
  • It displays the following on the console during encryption:

It accepts the following parameters:

  • -h → Help Menu
  • --path, -P → Encrypt the specified path
  • --host, -H → Remote address name or DNS
  • --domain, -d → Domain name, the default domain name is (.)
  • --user, -u → Username to be used for authentication, use it with remote host and password
  • --pwd, -p → Password to be used for authentication, use it with remote host and username
  • --uac, -ub Bypass UAC, default is false

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • ---CrossLock_readme_To_Decrypt---.txt
  • autorun.inf
  • boot.ini
  • bootfont.bin
  • bootsect.bak
  • bootmgr
  • bootmgr.efi
  • bootmgfw.efi
  • desktop.ini
  • iconcache.db
  • ntldr
  • ntuser.dat
  • ntuser.dat.log
  • ntuser.ini
  • thumbs.db

It avoids encrypting files found in the following folders:

  • AppData
  • Boot
  • Windows
  • Windows.old
  • temp
  • perflogs
  • Tor Browser
  • Internet Explorer
  • Google
  • Opera
  • Opera Software
  • Mozilla
  • Mozilla Firefox
  • $RECYCLE.BIN
  • $Recycle.Bin
  • System Volume Information
  • ProgramData
  • All Users
  • application data
  • Program Files
  • Program Files (x86)
  • #recycle
  • Perl64
  • Perl
  • Python3
  • Python27
  • Python
  • intel
  • msocache
  • $windows.~ws

It appends the following extension to the file name of the encrypted files:

  • {Original File Name}.{Original File Extension}.crlk

It drops the following file(s) as ransom note:

  • {Encrypted Directory}\---CrossLock_readme_To_Decrypt---.txt

It avoids encrypting files with the following file extensions:

  • .bak
  • .bat
  • .bin
  • .blf
  • .ckp
  • .cmd
  • .com
  • .crlk
  • .dacpac
  • .dat
  • .db-shm
  • .db-wal
  • .dbc
  • .diagcab
  • .diagcfg
  • .diagpkg
  • .dll
  • .exe
  • .hta
  • .icns
  • .idx
  • .inf
  • .key
  • .lnk
  • .lock
  • .log
  • .log1
  • .log2
  • .msi
  • .msstyles
  • .mwb
  • .nls
  • .ocx
  • .prf
  • .ps1
  • .reg
  • .regtrans-ms
  • .rnd
  • .scr
  • .search-ms
  • .sql
  • .sqlite
  • .sqlite3
  • .sys
  • .tmd

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.398.02

FIRST VSAPI PATTERN DATE:

21 Apr 2023

VSAPI OPR PATTERN File:

18.399.00

VSAPI OPR PATTERN Date:

22 Apr 2023

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 4

Identify and terminate files detected as Ransom.Win64.CROSSLOCK.THDAHBC

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 5

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.  
  • {Encrypted Directory}\---CrossLock_readme_To_Decrypt---.txt

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win64.CROSSLOCK.THDAHBC. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:

Step 7

Restore encrypted files from backup.


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